﻿using System;
using System.Collections.Generic;

namespace Loki.Engine
{
    public class EntityEqualityComparer<TEntityClass, TEntityKey> : EqualityComparer<TEntityClass> where TEntityClass : IAtomicEntity<TEntityKey>
    {

        public override bool Equals(TEntityClass x, TEntityClass y)
        {
            if (x == null || y == null)
                return x == null;
            else
                return Object.Equals(x.ID, y.ID);
        }

        public override int GetHashCode(TEntityClass obj)
        {
            return obj.ID.GetHashCode();
        }
    }

    public class LinkEqualityComparer<TEntityKey> : EqualityComparer<IEntityLink<TEntityKey>>
    {
        public override bool Equals(IEntityLink<TEntityKey> x, IEntityLink<TEntityKey> y)
        {
            if (x == null || y == null)
                return x == null;
            else
            {
                return Object.Equals(x.Left, y.Left) && Object.Equals(x.Right, y.Right);
            }
        }

        public override int GetHashCode(IEntityLink<TEntityKey> obj)
        {
            if (obj.Left == null && obj.Left == null)
                return 0;
            else if (obj.Right == null)
                return obj.Left.GetHashCode();
            else
                return obj.Left.GetHashCode() ^ obj.Right.GetHashCode();
        }
    }
}